While players and coaches huddled after a practice last week, Whalen, Minnesota’s veteran point guard, pointed to center Sylvia Fowles and chirped, “We have a birthday!” A staff member produced a sheet cake while the players sang a hip-hop version of “Happy Birthday to You.” Then they formed a gantlet, which Fowles ran through, cradling a basketball as teammates playfully snapped towels at her.

“Off the court, she’s the one who keeps the locker room light, funny,” Maya Moore, the former W.N.B.A. most valuable player, said of Whalen. “She’s the first one that tries to make it fun, make sure everybody’s O.K. And if somebody needs a little pick-me-up, she notices. She’s a big sister by nature. That helps us on and off the court.”

With the 34-year-old Whalen as the catalyst, the defending champion Lynx reached the finals for the fifth time in six years — all since Whalen arrived in a 2010 trade from Connecticut.

If Minnesota beats the Los Angeles Sparks in the best-of-five finals — Game 1 is Sunday at the Target Center — not only will the W.N.B.A. have its first repeat champion since the Sparks in 2001-2, but Minnesota will match the Houston Comets’ record four titles. The Lynx won in 2011, 2013 and 2015.

A healthy Whalen is enjoying this season a lot more than last, and not just because she collected her second Olympic gold medal in August.

Worn out from playing overseas in the winter and the W.N.B.A. in the summer, Whalen had an aching right ankle and Achilles’ tendon through the final weeks of last season. She missed the final four regular-season games and five in all, posting the fewest assists of her career (125) and her lowest scoring average since 2006 (10.9 points). Heading into the playoffs, Whalen was so down that the assistant coach Jim Petersen took to texting her a well-known quote from the former Houston Rockets coach Rudy Tomjanovich: “Don’t ever underestimate the heart of a champion.”

Whalen needed last-minute treatment to suit up for Game 2 of the conference semifinals. In the decisive Game 5 of the finals against Indiana, Whalen badly sprained the ankle in the first quarter. She limped through the 69-52 victory, finishing with 2 points and 4 assists in 17 minutes. But pain and swelling forced Whalen home early from the victory party at Paisley Park, the home and recording studio of the late artist Prince.

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“Lindsay makes it seem like a sprained ankle is nothing to deal with,” Lynx Coach Cheryl Reeve said. “If you saw her ankle following the game — the discoloration and swelling, so soon with the injury — you would understand what a warrior she was.”

Months before, Whalen realized the toll that year-round play was taking. She chose to skip the overseas season for the first time in a decade, giving up a six-figure salary to let her body heal.

“I could feel that the years had kind of caught up to me, and I needed to take a break if I wanted to play really well here again,” Whalen said.

Once the pain subsided, Whalen began a specialized training program for pro athletes called Exos, which focused on core strength, flexibility and nutrition.

“You feel lean, and it tightens everything up,” Whalen said.

Reeve and Lynx General Manager Roger Griffith traded for the veteran San Antonio guard Jia Perkins on draft day, completing an overhaul of the team’s bench. Perkins and the previously acquired Anna Cruz and Renee Montgomery eased the backcourt load on Whalen and the six-time All-Star guard Seimone Augustus.

Diana Taurasi, the Phoenix Mercury star and Whalen’s Olympic teammate, noticed a more spry Whalen at an Olympic team camp in February. Whalen reported to Lynx training camp in April refreshed and healthier than in years.

Reeve limited Whalen’s minutes to a career-low 24.6 per game, leading to fewer points (9.8 per game after nine consecutive seasons in double figures) and assists (a career-low 3.8). But Whalen shot a career-best .513 from the field while missing only two games, neither because of injury. And at big moments, Whalen excelled.

At her best, Whalen rises to a level that Augustus, another Olympic teammate, calls “Weezy mode” — determined, physical and demonstrative, with big plays punctuated by a downward fist pump. The nickname is a nod to the rapper Lil Wayne, a Whalen favorite. “When that’s activated, you always see our team go on a run or get a defensive stop,” Augustus said.

Augustus saw it in the gold medal game in Rio, when Whalen delivered 17 points and 6 assists off the bench as the United States dismissed Spain, 101-72. It surfaced in Minnesota’s three-game semifinal sweep of Phoenix, when Whalen averaged 15.3 points while shooting 66.7 percent from the field.

Whalen had 19 points and 7 assists in just 24 minutes in Game 1, scoring 12 in the fourth quarter, with a backbreaking 3-pointer in the final seconds. She added 16 points in Game 2, then 11 points and 5 assists in the clinching Game 3.

“She made a really smart decision by deciding to take some time off in the off-season,” the ESPN analyst LaChina Robinson said. “What I see in Lindsay Whalen is a player who is faster in transition. That midrange jump shot in Game 3 against Phoenix had a lot of lift on it.”

Robinson continued: “I appreciate everything Minnesota brings off the bench. But it is Lindsay Whalen, her fire, her determination, her competitive spirit, that is at the core of that team. That she is in the best physical shape we’ve seen her going into a finals appearance bodes well for Minnesota.”

A version of this article appears in print on October 9, 2016, on Page SP12 of the New York edition with the headline: Healthy and Rested, a Lynx Star Is Primed for the Finals. Order Reprints|Today's Paper|Subscribe